```final boolean b final double d final Random rng = new Ran kotlinlang #announcements

09/27/2017, 1:59 PM

final boolean b;
final double d;
{
    final Random rng = new Random();
    final double r = rng.nextDouble();
    if (r < 0.5d) {
        b = false;
        d = r / 2;
    } else {
        b = true;
        d = r * 3;
    }
    // rng and r fall out of scope
}

Is it possible to express this in kotlin? using a run {} "block" is a lambda, and captured value initialization is forbidden.

09/27/2017, 2:03 PM

init

Something like this:

val b:Boolean
val d:Double

init {
    val rng = Random()
    val r = rng.nextDouble()
    if (r < 0.5) {
        b = false
        d = r / 2
    } else {
        b = true
        d = r * 3
    }
}

09/27/2017, 2:06 PM

init is only valid grammar for a class, correct? what about inside a function?

09/27/2017, 2:07 PM

That's right. Hmm

neil.armstrong

09/27/2017, 2:08 PM

fun main(args: Array<String>) {
    var b: Boolean
    var d: Double

    {
        val rng = Random()
        val r = rng.nextDouble()
        if (r < 0.5) {
            b = false
            d = r / 2
        } else {
            b = true
            d = r * 3
        }
    }()
}

though not sure why you’d want it like that?

09/27/2017, 2:09 PM

In this case you could sort of fake it by destructuing a pair, but lets say you had > 3 initializations to do

09/27/2017, 2:10 PM

That doesn't work @neil.armstrong. You get this compiler error: "Captured values initialization is forbidden due to possible reassignment".

09/27/2017, 2:10 PM

@neil.armstrong In that code they are var, not val

neil.armstrong

09/27/2017, 2:10 PM

09/27/2017, 2:10 PM

Ah, didn't see the

var

But is it really that important for

rng

to leave the scope?

09/27/2017, 2:12 PM

This is a really contrived example. In truth I have some fairly heavyweight object that is recycled in an object pool

I have to call the recycle method on it, and using it after that is a runtime error